1. Field of Invention
The present invention relates generally to the field of wireless communication and data networks. More particularly, in one exemplary aspect, the present invention is directed to compensating for or mitigating the effects of electro-magnetic signal interference in devices implementing two or more wireless air interfaces or protocols.
2. Description of Related Technology
The effective implementation of convergence products has led to a revolution in the way consumers view computerized devices. These next generation computerized devices focus on offering consumers a substantially unified solution for a variety of services to which consumers have become accustomed. Examples of such a converged solution include the exemplary Macbook Air™ laptop computer, and iPhone™ smartphone, each manufactured by the Assignee hereof, and each which support a variety of wireless protocols and other functions. For instance, the aforementioned iPhone smartphone has the capability of, among other things, sending and receiving data over a WLAN network, making and receiving calls using a GSM cellular network, and operating wireless peripheral equipment (such as wireless headsets or Human Interface Devices (HIDs)) using the Bluetooth protocol.
As technologies converge, implementation requirements and constraints, including cost, size, and antenna isolation in these hardware systems inevitably introduce difficulties which can potentially result in a poor user experience with the device. For example, both Bluetooth and WLAN (802.11b/g/n) share the same ISM band in the 2.4-2.4835 GHz frequency range. Due to the close physical proximity of these wireless interfaces (including their antenna) in these converged or unified devices, the Bluetooth and WLAN technologies can interfere with each other when operating simultaneously, and can cause problems such as for example Bluetooth audio stutter and drop-outs, slow WLAN transfer speeds, poor Bluetooth mouse (MS) tracking, link dropouts, etc.
In devices where the physical configuration of the device can change, such as in the exemplary case of a clamshell-type laptop computer or smartphone, most 2.4 GHz WLAN and Bluetooth coexistence solutions focus exclusively on open-lid cases for these portable systems, as this is a common usage scenario (in that the display is presumed to be viewable by the user during use). However, this common usage scenario can no longer be taken for granted as other devices, such as external displays, continue to improve and become increasingly affordable opening up many new applications where the device is intended for operation in a “clamshell” mode (i.e., closed-lid) physical configuration. There is a reasonable user expectation for Bluetooth and WLAN performance in this mode to be on par with open-lid use.
Moreover, aside from traditional clamshell-type arrangements, yet other form factors for computers and portable devices such as smartphones are emerging. For instance, the outer/display cover on some smartphones slides laterally to expose the display and keypad on some models, or one portion of the housing may fit at least partly within the other.
In some cases, the foregoing devices utilize partly or completely metallic casings or housings, which can further exacerbate the effects of interference (partly in that the number of options for placement of the two or more antennas are significantly reduced over a non-metallic case due to inter alia, antenna isolation considerations).
There are a number of technical challenges in closed-lid/cover operation that can adversely affect wireless performance. Often, since design goals are set up to ensure acceptable open-lid performance, it is not uncommon for the clamshell operation of the device to be compromised. For example, WLAN and BT antenna efficiencies may decrease, antenna patterns can change, and WLAN/BT antenna isolation may be greatly reduced (and platform noise may increase) in closed-lid mode, as compared to an open-lid physical configuration. In terms of user-experience this can translate to slower data rates when web-surfing or uploading/downloading data, jerky BT mouse or touchpad tracking, and interrupted BT headset/headphone audio, among other effects of co-located air interface interference.
Accordingly, improved methods and apparatus for dynamically compensating for the effects of interference between wireless technologies that at least partly operate in the same frequency bands are needed, that recognize that performance characteristics can change (sometimes quite significantly) based on the physical configuration of the device. Ideally, such methods and apparatus would also ultimately provide the user with the best user experience possible, while offering converged services in a unified client device in a space- and power-efficient manner. In addition, such methods and apparatus would also ideally take into account the different ways the device is typically used in these different physical configurations.